Abstract: Our laboratory has demonstrated that an effective way to generate antigen-specific CTLs is by using dendritic cells (DCs) as antigen presenting cells. We have developed a method for obtaining these cells in large numbers from blood monocyte precursors and mature them ex vivo to enhance their potency. In our first clinical study, a single subcutaneous injection of mature monocyte-derived antigen-pulsed DCs rapidly and dramatically boosted both CD4+ve and CD8+ve T cell responses in healthy volunteers. In this study, we will examine the impact of DC maturational state and route of administration on the immunogenicity of DCs in healthy volunteers. Hypothesis: Maturational state and route of injection of DCs will affect their immunogenicity, and the nature of T helper (Th) phenotype. Mature DCs will be more immunogenic and lead to greater Th 1 skewing than immature DCs. Intradermal administration will be superior to the subcutaneous route.